Semiconductor device features become smaller and smaller as design and fabrication techniques for the semiconductor devices improve. As feature sizes get smaller, in some semiconductor devices, signal routing densities may be more important to die size than transistor densities.
In addition, signals generally cannot be routed over some portions of a semiconductor device. Some areas of a semiconductor device may be safe for signal routing and some areas of a semiconductor device may not be safe for signal routing. In some devices, signals that are unrelated to the operation of a particular transistor are not routed over the active region of that transistor because the signals may influence normal operation of that transistor. In other cases, signals may be routed above active regions of transistors but at a height above the transistors, with sufficient dielectric material between the signal and the active region, such that any capacitive coupling between the signal and the active regions has a negligible effect on transistor operation.
Thus, devices with high signal routing densities, such as, for example, devices with repeatable arrays, may require an increased die size due to the signal routing requirements discussed above. In other words, while die size might be reduced if only the transistor densities were considered, in practice die size grows simply to accommodate the necessary signal routing.
The inventor has appreciated that there is a need for ways to improve signal routing options relative to device densities in an effort to reduce real estate consumed on a semiconductor device for a given function.